1. Field of the Invention
The present invention concerns a braking system for electric step motors, which step motors operate in conjunction with a light assembly comprising a moving head for pan or tilt of the light assembly or operating in the lamp for moving internal optical components, which step motors during operation are connected to driving means.
2. Description of Related Art
U.S. Pat. No. 4,179,646 describes a circuit breaker motor operator control circuit which utilizes the voltage developed across a dynamic braking resistor during breaking of a permanent magnet DC motor to prevent re-energization of the motor until it has been braked to a virtual stop. The control circuit also includes a timing network operating to prevent continued pumping of the breaker operating mechanism by the motor operator should the operating mechanism for some reason fail to become charged within a prescribed time period.
JP 8322295 concerns a stepping motor which can stop rotation perfectly when a power supply is cut off. If energization of a driver is cut off, a stepping motor is put into a non-exciting state and, at the same time, relays are opened. As a result, closed circuits are composed of windings of the step motor is established. If a force is applied to the rotary shaft of the stepping motor in this state and the permanent magnets of a rotor are turned, induced currents are respectively applied to the closed circuits composed of the respective windings and magnetic forces are generated between the respective windings and the permanent magnets of the rotor so as to produce interactions between the windings and magnets, so that the rotor is braked.
The stepping motor described in JP 8322295 is used in a ball counter in a ball rental machine installed in an amusement center. This JP application is from a different technical field, far from light assemblies comprising moving heads.